The purpose of this Core is to stimulate a collaborative multidisciplinary program of research on how environmental exposures at particular stages in the life cycle affect susceptibility to disease and to deficits in development. The objectives of the Developmental Susceptibility Research Core are to: foster and expand collaborative research on the effects of exposures during vulnerable stages in development, including adverse outcomes of pregnancy, birth defects, neurodevelopmental deficits, childhood cancer, and asthma; establish effective mechanisms for sharing ideas, discussing research in progress, and fostering new interdisciplinary ventures that integrate laboratory, clinical, and epidemiologic approaches to developmental studies; and promote incorporation of molecular and genetic markers into traditional epidemiology studies of reproductive and developmental outcomes. Developmental Susceptibility Core investigators are engaged in a broad spectrum of research ranging from studies of embryologic development and mechanisms of birth defects to epidemiologic investigations of environmental and occupational exposures in relation to complications and adverse outcomes of pregnancy, neurodevelopment, and childhood cancer.